Automotive dash and control panels have been designed to incorporate an ever increasing array of controls and features. These features must not only provide a wide range of services, they must do so reliably from within the automotive interior, an environment prone to stressors such as heat, cold, moisture, and vibration. These environmental conditions dictate robust controls capable of providing vehicle occupants with simple and reliable functioning over the vehicle lifespan. In this regard, automotive designers spend considerable effort to improve existing controls to improve their robustness and reliability.
One area of such development has come from the use of field-effect sensors. Field-effect sensors allow controls to be isolated from direct contact with the operator and therefore can be placed behind protective surfaces within the automotive interior. This provides a simple and effective alternative to complex waterproofed button assemblies that add cost through both design and manufacturing. The field-effect sensors detect an operators touch through a sealed protective surface without requiring mechanical movement of that surface. Although field-effect sensors provide obvious benefits for use as automotive controls, they provide unique design challenges to designers.
One challenge to design and manufacturing stems from the nature of field-effect sensors. It is known that these sensors must be secured in close proximity behind a face plate or similar surface such that they will properly function when the surface is touched. Complex or curved surfaces provide considerable challenge to designers as the sensor assembly must follow closely the contours to provide reliable functioning. The present manufacturing technique has been to use adhesive between the field-effect sensors and the face plate to insure both proximity as well as contour correlation. This provides a significant manufacturing concern. No manufacturing process is flawless. Improper installation, orientation, or part manufacture may require disassembling of the sensor assembly. In cases wherein adhesive was utilized to affix the sensors, it is common for the sensors or the circuit assembly to which they are attached to experience delamination or similar damage. The cost of such electronics makes such damage highly undesirable. Additionally, remaining dried adhesive on the attachment surface may interfere with installation of a replacement sensor assembly. Therefore, present assembly techniques using adhesive generate costly manufacturing concerns as well as impediments to long-term maintenance.
It would, therefore, be highly desirable to have an automotive center stack instrument control assembly utilizing field-effect sensor technology without requiring the use of adhesives to attach the sensors to their corresponding mounting surfaces. Additionally, it would be highly desirable to have such an assembly wherein the sensors were adaptable to complex surface contours.